1. Field of the Invention
The present invention relates to a method and apparatus for drawing a fiber from a blank, more particularly, a method and apparatus for drawing an optical waveguide fiber from a silica-containing blank.
2. Description of the Related Art
Optical waveguide fibers (optical fibers) are a transmission medium used in optical communication systems. Optical fibers are typically made by well known methods that involve forming blanks from which the fibers are to be drawn, storing the blanks in holding ovens, and drawing fibers from the blanks in draw furnaces.
Strength is an important characteristic of optical fibers. Particulate contaminants on the fiber surface often weaken the fiber and cause flaw initiation and fiber failure under tensile loading. Some optical fibers, particularly those drawn in zirconia (ZrO2) muffle furnaces, break under low stress due to such contaminants.
An object of the present invention is to improve the strength of fibers.
Another object of the invention is to remove break sources that cause fibers to break at low stress.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
As explained more fully below, it has been determined that breaking optical fibers contain silicon carbide (SiC) and silicon nitride (Si3N4) refractory contaminants that cause the fibers to fail at low stress. The present invention improves the strength of fibers by removing the contaminants through active oxidation during the fiber-drawing process.
To achieve the objects and in accordance with the purpose of the invention, as broadly described herein, the invention provides an improved method of producing a fiber in a drawing device having a refractory, oxide component in a drawing portion, comprising the steps of disposing a blank having a refractory contaminant in the drawing portion, providing an environment in the drawing portion that causes active oxidation of the refractory contaminant, and drawing a fiber from the blank in the environment.
The invention also provides an improved apparatus for producing a fiber, comprising a drawing portion that has a refractory, oxide component and that heats a blank having a refractory contaminant, a supply device that supplies gas to the drawing portion to provide an environment in the drawing portion that causes active oxidation of the refractory contaminant, and a device for drawing a fiber from the blank in the environment.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and together with the description, serve to explain the principles of the invention.